In general, a vacuum heat insulation material is manufactured by inserting a core material into an outer covering material with a bag shape and reducing pressure inside the outer covering material. Fins are formed on the outer periphery of the vacuum heat insulation material, the fins not interposing the core material therebetween and being made from only the outer covering material.
Such a vacuum heat insulation material is used by bending the fins described above to the horizontal plane side of the outer covering material and superimposing the fins on the outer covering material (for example, refer to PTL 1 and PTL 2).
FIG. 13 is a diagram illustrating a sectional structure of vacuum heat insulation material 100 of the background art described in PTL 1.
Vacuum heat insulation material 100 has outer covering material 102 in which core material 101 is vacuum sealed. Fin 103 which is provided on a peripheral edge of outer covering material 102 is bent and superimposed on the horizontal plane of outer covering material 102 (horizontal plane of a longitudinal direction (vertical direction) in the drawings). Fin 103 is fixed by being pasted to the horizontal plane using fixing member 104 such as tape, and is incorporated in heat insulation wall 105 of a refrigerator.
In this manner, since fin 103 is used superimposed and fixed on the horizontal plane of outer covering material 102, flow of a foam heat insulation material such as a rigid polyurethane foam is not inhibited by fin 103 (peripheral edge portion). Consequently, it is possible to obtain vacuum heat insulation material 100 with a favorable heat insulation property without generating an air pocket, a void, a urethane unfilled part, and the like.
FIG. 14 is a diagram illustrating a configuration of a bent unit in vacuum heat insulation material 100 in the background art.
Outer covering material 102 of vacuum heat insulation material 100 is formed of a laminated sheet (hereinafter, referred to as an outer covering material sheet) on which a gas barrier layer made from aluminum foil and the like, a thermally fused layer, and a protective layer are laminated, and has flexibility. Then, the bent unit on the side surface of the outer covering material sheet is configured by fin 103 that is formed by overlapping two outer covering material sheets. Therefore, the bent unit has quite high rigidity and strength. Therefore, as shown in FIG. 14, bent part 103a of fin 103 protrudes from side surface 100a of vacuum heat insulation material 100.
Since fin 103 on side surface 100a side and fin 103 on side surface 100b on a side which intersects with fin 103 on side surface 100a side overlap, bent part 103a is large on a corner that is orthogonal to two sides of side surfaces 100a and 100b of vacuum heat insulation material 100. In addition, an amount of protrusion of protrusion 107 is larger than an amount of protrusion of bent part 103a which is formed in a center part other than the corner of side surface 100a, that is, a longitudinal direction part.
In particular, when a case is assumed in which outer covering material 102 is a three-sided bag type that is formed by fusing three sides of the two outer covering material sheets, outer covering material 102 includes at least four or more sheets (two or more fins) of outer covering material sheets of two sheets (one fin) of outer covering material sheets of fin 103 on side surface 100a side and two sheets (one fin) of outer covering material sheets of fin 103 on side surface 100b side in protrusion 107 of bent part 103a. Protrusion 107 of the corner formed in this manner is particularly large in comparison to the amount of protrusion of bent part 103a which is generated in the center part of a side other than the corner.
Presence of such protrusion 107 hardly influences flow of the foam heat insulation material such as a rigid polyurethane foam from the viewpoint of the flow being inhibited due to fin 103 and does not cause substantial reduction in a heat insulation property.
However, recently, the high heat insulation property of the vacuum heat insulation material has gained attention, while the application thereof is also developed in the heat insulation wall of a house, a refrigerated container, and the like. In a case of use in such an application, it is often the case that a thick vacuum heat insulation material is used. Therefore, in a case where a plurality of vacuum heat insulation materials 100 are used disposed lined up, protrusions 107 are in a state of abutting with each other, a gap is generated between each adjacent vacuum heat insulation material 100, and the heat insulation property as the heat insulation wall is impaired. Therefore, it becomes necessary for the gap that is generated between each vacuum heat insulation material 100 to be filled in by a heat insulation material, for example, glass wool and the like.